In U.S. Pat. Nos. 3,486,241 and 3,694,925, assigned to the same assignee as the present application, railway cars are disclosed in which circulating air passes throughout the lading, through an air conditioning unit and back to the lading. Through the use of these air conditioned cars, it is possible to transport perisable or damagable ladings in bulk. Considerably less damage to the lading in hopper cars is observed than with a hopper car not utilizing conditioned air.
However, one problem which the use of conditioned air does not solve is the problem of the pressure that the weight of the lading in the upper portion of the car exerts on the lading in the lower portion. While the general shape of some railway cars, such as hopper cars, functions to distribute the lading weight somewhat, the hopper shape is not sufficient to avoid damage to the lading caused by the upper lading weight acting upon the lower lading, particularly if the hopper car is full.
The problem of damage to lading caused by the weight of the upper lading on the lower lading is, of course, not limited to air conditioned cars, but is rather a problem common to nearly all bulk lading transfer where the lading is of a perishable or damagable type and an upper bulk portion exerts a force or weight on a lower bulk portion.